This invention relates to an image processing apparatus and an image processing method as well as a recording medium, and more particularly to an image processing apparatus and an image processing method as well as a recording medium which can be suitably applied to a network which complies with the standard of the IEEE (Institute of Electrical and Electronics Engineers) 1394 or the like.
Communication in accordance with the IEEE 1394 standard which is one of standards for a digital interface allows isochronous transfer of data and therefore is suitable for transfer of data which need be played back on the real time basis such as image and sound data. Further, also from an increase in demand for communication of multimedia data in recent years, much attention is paid to the communication in accordance with the IEEE 1394 standard.
FIG. 1 shows a configuration of an example of an AV (Audio Visual) system (the term “system” is used herein to signify a plurality of apparatus gathered logically irrespective of whether or not the apparatus are accommodated in the same housing) which allows communication in accordance with the IEEE 1394 standard.
The AV system of FIG. 1 includes a hard disk recorder 31 and a digital television monitor 32 of the DV (Digital Video) system which are IEEE 1394 apparatus as apparatus which comply with the IEEE 1394 standard, and an IEEE 1394 cable 3. The hard disk recorder 31 and the digital television monitor 32 are connected to each other by the IEEE 1394 cable 3.
It is to be noted that, in the following description, in order to avoid complicated description, description is given only of image data from between image data and sound data. Further, it is assumed basically that an image played back by the hard disk recorder 31 is transmitted through the IEEE 1394 cable 3 to the digital television monitor 32 by which it is outputted (displayed).
The hard disk recorder 31 includes a hard disk 41, a signal processing circuit 42, an interface circuit 43, and a control circuit 44.
The signal processing circuit 42 performs necessary signal processing for image data supplied thereto from the interface circuit 43 and supplies the processed image data to the hard disk 41 so as to be recorded onto the hard disk 41. Further, the signal processing circuit 42 plays back (reads out) image data recorded on the hard disk 41, performs necessary signal processing for the image data and supplies the processed image data to the interface circuit 43.
The interface circuit 43 functions as an interface for allowing communication compliant with the IEEE 1394 standard to be performed. In particular, the interface circuit 43 converts the format of image data and other data supplied thereto from the signal processing circuit 42 into that of data compliant with the IEEE 1394 standard, and transmits the resulting data to the IEEE 1394 cable 3. Further, the interface circuit 43 receives image data and other data from the IEEE 1394 cable 3, converts the format of the received data back into its original format and supplies the data of the original format to the signal processing circuit 42.
The control circuit 44 controls the signal processing circuit 42 and the interface circuit 43, for example, in response to a request and so forth from the digital television monitor 32 received by the interface circuit 43.
The digital television monitor 32 includes an interface circuit 51, a signal processing circuit 52, a display unit 53, a control circuit 54 and an operation panel 55.
The interface circuit 51 functions as an interface for allowing communication compliant with the IEEE 1394 standard to be performed similarly to the interface circuit 43, and transmits image data and so forth supplied thereto from the signal processing circuit 52 to the IEEE 1394 cable 3. Further, the interface circuit 51 receives image data and other data from the IEEE 1394 cable 3 and supplies them to the signal processing circuit 52.
The signal processing circuit 52 performs necessary signal processing for image data supplied thereto from the interface circuit 51 and supplies the processed image data to the display unit 53. Further, the signal processing circuit 52 supplies various requests and so forth from the control circuit 54 to the interface circuit 51 so as to be transmitted through the IEEE 1394 cable 3.
The display unit 53 is formed from, for example, a CRT (Cathode Ray Tube) or a liquid crystal panel and displays image data from the signal processing circuit 52.
The control circuit 54 controls the interface circuit 51 and the signal processing circuit 52 in accordance with an operation signal or the like from the operation panel 55.
The operation panel 55 includes buttons and so forth to be operated in order to input various instructions such as playback of image data, pause or fast feeding, and supplies an operation signal corresponding to an operated button to the control circuit 54. It is to be noted that the operation panel 55 may otherwise be a panel provided integrally on the digital television monitor 32 or a remote commander for remotely controlling the digital television monitor 32.
Now, operation of the AV system of FIG. 1 is described.
In the AV system of FIG. 1, if the power supply to the hard disk recorder 31 and the digital television monitor 32 is placed into an on state, then the interface circuit 43 of the hard disk recorder 31 and the interface circuit 51 of the digital television monitor 32 recognize IEEE 1394 apparatus connected thereto by the IEEE 1394 cable 3 (in FIG. 1, the hard disk recorder 31 and the digital television monitor 32) and establish a logical channel (data channel) for use for delivery of data and another logical channel (control channel) for use for delivery of a control signal. Then, between the hard disk recorder 31 and the digital television monitor 32, data and a control signal are delivered through the channels.
First, for example, in order to cause the hard disk recorder 31 to record image data, the user will connect an image inputting apparatus (not shown) which can input an image such as a video camera to the interface circuit 43 using the IEEE 1394 cable 3, and operate the image inputting apparatus to input image data to the hard disk recorder 31. The image data are received by the interface circuit 43 and supplied to the signal processing circuit 42.
The signal processing circuit 42 performs necessary signal processing for the image data from the interface circuit 43 such as, for example, coding into image data of the DV system and supplies the resulting image data to the hard disk 41 so as to be recorded onto the hard disk 41.
It is to be noted that recording of an image by the hard disk recorder 31 may otherwise be performed, for example, in the following manner. In particular, if the digital television monitor 32 has an input terminal provided thereon, then image data can be inputted to the digital television monitor 32 through the input terminal. Thus, the image data are coded into image data of the DV system by the signal processing circuit 52, and the image data of the DV system are supplied from the interface circuit 51 through the IEEE 1394 cable 3 to the hard disk recorder 31 so as to be recorded by the hard disk recorder 31.
On the other hand, in order to play back image data recorded by the hard disk recorder 31 and transmit the image data to the digital television monitor 32 so that the image data are displayed, the user will operate the button (playback button) of the operation panel 55 for inputting a playback (normal playback) instruction. In this instance, the operation panel 55 supplies an operation signal for a normal playback instruction to the control circuit 54. The control circuit 54 receives the operation signal for a normal playback instruction and sets the operation mode of the apparatus to a normal playback mode. After the normal playback mode is entered, the interface circuit 51, signal processing circuit 52 and display unit 53 are placed into an input waiting state for image data.
Further, the control circuit 54 controls the interface circuit 51 to transmit a mode signal representing that the normal playback mode is entered to the hard disk recorder 31 through the control channel of the IEEE 1394 cable 3.
The mode signal is received by the interface circuit 43 of the hard disk recorder 31. When the mode signal is received, the interface circuit 43 supplies the mode signal to the control circuit 44. The control circuit 44 changes the operation mode of the apparatus in accordance with the mode signal from the interface circuit 43. In the present case, the normal playback mode is established as the operation mode.
After the normal operation mode is entered, the signal processing circuit 42 starts playback of image data from the hard disk 41. It is to be noted that, if the user operates the operation panel 55 to designate image data (contents) to be played back, then the signal processing circuit 42 starts playback of the image data designated by the user beginning with the top of the image data. On the other hand, for example, if the user does not particularly designate image data to be played back, then the signal processing circuit 42 starts playback from a position of the hard disk 41 determined in advance (for example, from a position at which the last playback ended). Here, if the user operates the operation panel 55 to designate contents to be played back, then a signal representative of the designated contents is transmitted from the digital television monitor 32 to the hard disk recorder 31 through the control channel of the IEEE 1394 cable 3.
The signal processing circuit 42 decodes the image data played back from the hard disk 41 and outputs the decoded image data from an output terminal not shown. In particular, since image data of the DV system are recorded on the hard disk 41, when the image data are to be outputted from the output terminal, the signal processing circuit 42 decodes the image data of the DV system into image data of, for example, the NTSC system and then outputs the image data of the NTSC system from the output terminal.
Further, the signal processing circuit 42 supplies the image data of the DV system played back from the hard disk 41 to the interface circuit 43. The interface circuit 43 transmits the image data of the DV system from the signal processing circuit 42 to the digital television monitor 32 through the data channel of the IEEE 1394 cable 3.
Accordingly, here, image data compression coded in accordance with the DV system are transmitted from the hard disk recorder 31 to the digital television monitor 32 through the IEEE 1394 cable 3. It is to be noted that, although it is possible to transmit image data of the NTSC system or the like obtained by decoding image data of the DV system from the hard disk recorder 31 to the digital television monitor 32, between different IEEE 1394 apparatus, image data of the DV system are usually communicated as they are.
The image data transmitted from the hard disk recorder 31 through the IEEE 1394 cable 3 in such a manner as described above are received by the interface circuit 51 of the digital television monitor 32. The interface circuit 51 supplies the image data to the signal processing circuit 52. The signal processing circuit 52 decodes the image data of the DV system from the interface circuit 51 into image data of, for example, the NTSC system and supplies the resulting image data to the display unit 53 so that the image data are displayed on the display unit 53.
Then, if the user operates, for example, the button (fast feed button) of the operation panel 55 for inputting an instruction for fast feeding, then the operation panel 55 supplies an operation signal for a fast feed instruction to the control circuit 54. In this instance, the control circuit 54 controls the interface circuit 51 to transmit a mode signal for instruction to set a fast feed mode to the hard disk recorder 31 through the IEEE 1394 cable 3.
The mode signal for instruction to establish the fast feed mode is received by the interface circuit 43 of the hard disk recorder 31 and supplied to the control circuit 44. The control circuit 44 receives the mode signal and sets the operation mode of the apparatus to the fast feed mode.
After the fast feed mode is entered, the signal processing circuit 42 plays back the image data for each N frames from the hard disk 41.
While image data compression coded in accordance with the DV system are recorded on the hard disk 41, since the data amount per one frame in the DV system is fixed and the data of the DV system include only intra-coded images without involving interframe coding, it is possible to play back image data of the DV system for each plurality of frames. It is to be noted that it is otherwise possible to record image data compression coded in accordance with a system which involves interframe coding such as, for example, the MPEG system on the hard disk 41. In this instance, for detection of a recorded position of image data of a predetermined frame, a method disclosed in Japanese Patent Laid-Open No. Hei 6-325553(1994) or No. Hei 11-312381(1999) filed for patent in Japan by the assignee of the present application can be adopted.
If the signal processing circuit 42 plays back image data after each N-1 frames from the hard disk 41, then N-fold speed playback is performed.
The signal processing circuit 42 supplies the image data played back from the hard disk 41 to the interface circuit 43. The image data are thereafter transmitted to the digital television monitor 32 in a similar manner to that in the normal playback mode.
The digital television monitor 32 controls the display unit 53 to display the image data from the hard disk recorder 31 in a similar manner to that in the normal playback described hereinabove. In this instance, since the image data transmitted thereto from the hard disk recorder 31 are data of frames at intervals of N frames, moving pictures in a fast fed state are displayed on the display unit 53.
Then, if the user operates, for example, the button (pause button) of the operation panel 55 for inputting a pause instruction, then the operation panel 55 supplies an operation signal for a pause instruction to the control circuit 54. In this instance, the control circuit 54 controls the interface circuit 51 to transmit a mode signal for instruction of the pause mode to the hard disk recorder 31 through the IEEE 1394 cable 3.
The mode signal for instruction of the pause mode is received by the interface circuit 43 of the hard disk recorder 31 and supplied to the control circuit 44. The control circuit 44 receives the mode signal and sets the operation mode of the apparatus to the pause mode.
After the pause mode is entered, the signal processing circuit 42 supplies image data of the same frame obtained by repetitively playing back a frame of the image data, which has been played back last from the hard disk 41, from the hard disk 41 to the interface circuit 43. The interface circuit 43 transmits the image data from the signal processing circuit 42 to the digital television monitor 32 through the IEEE 1394 cable 3. It is to be noted that the hard disk recorder 31 may additionally include a frame buffer between the hard disk 41 and the signal processing circuit 42 such that image data of the same frame are read out not from the hard disk 41 but from the frame buffer.
The digital television monitor 32 controls the display unit 53 to display the image data from the hard disk recorder 31 in a similar manner as in the normal playback. In this instance, the image data transmitted from the hard disk recorder 31 are data of the same frame as described above, and therefore, moving pictures of a pause state (that is, an image in a still state) are displayed on the display unit 53.
Thereafter, if the user operates, for example, the playback button of the operation panel 55 for canceling the pause and designating playback (normal playback), then the operation panel 55 supplies an operation signal for a normal playback instruction to the control circuit 54. In this instance, the control circuit 54 controls the interface circuit 51 to transmit a mode signal for instruction of the normal playback mode to the hard disk recorder 31 through the IEEE 1394 cable 3.
The mode signal is received by the interface circuit 43 of the hard disk recorder 31 and supplied to the control circuit 44. In this instance, the control circuit 44 sets the operation mode of the apparatus to the normal playback mode.
After the normal playback mode is entered, the signal processing circuit starts playback of the image data beginning with a frame next to the frame which has been played back repetitively in the pause mode. The image data thus played back are transmitted to the digital television monitor 32 and displayed on the display unit 53 in a similar manner as described above.
Accordingly, moving pictures next to the image of a still state are displayed by the digital television monitor 32.
As described above, in the AV system described above, even if a pause instruction is issued, image data of the same frame are transmitted repetitively through the IEEE 1394 cable 3. In other words, also when a pause mode is established, image data are transmitted occupying a transmission bandwidth similar to that in normal playback. More particularly, where the image data to be transmitted are data, for example, of the NTSC system, they are transmitted occupying a transmission bandwidth corresponding to 29.97 frames/sec.
Accordingly, although there is no particular problem if the communication of the IEEE 1394 standard is used only for transmission of the image data, if it is used also for delivery of data by another application, a limited transmission bandwidth is used by transmission of image data of the same frame and the delivery of data by another application is limited. Thus, the transmission bandwidth is not utilized efficiently.
Further, in the AV system described above, after the user operates the operation panel 55, image data to be displayed are transmitted without fail from the hard disk recorder 31 to the digital television monitor 32. Therefore, the responsibility after the user operates the operation panel 55 until an image is displayed is sometimes low.